1. Field of the Invention
The present invention relates to handheld rangefinders that assist a user in compensating for deviations in projectile trajectory. More particularly, the present invention relates to a handheld rangefinder that utilizes a range sensor and a tilt sensor to determine hold over ballistic information corresponding to projectile trajectories.
2. Description of the Related Art
Hunters and other firearm and bow users commonly utilize handheld rangefinders to determine ranges to targets. Generally, handheld rangefinders utilize lasers to acquire ranges for display to a hunter. Utilizing the displayed ranges, the hunter makes sighting corrections to facilitate accurate shooting. Unfortunately, due to variations in elevation and slope, the ranges determined by handheld rangefinders often are not accurate representations of the horizontal distances projectiles must travel.
For example, as shown in FIG. 1, a hunter positioned above or below a target may be provided a range, 9 yards for instance, that is different than the actual horizontal distance to the target, 5 yards for instance, thereby resulting in inaccurate shooting. Further, handheld rangefinders fail to determine hold over ballistic information corresponding to the amount by which hunters must vary their aim, thereby forcing hunters to manually perform hold over calculations.
Devices operable to compensate for slope and elevation utilizing lasers and inclinometers have been developed to alleviate some of these problems. For example, U.S. patent application Ser. Nos. 10/867,429 and 10/964,206, which are incorporated herein by reference, disclose telescope sights and other optical devices having a laser range sensor and an inclinometer. Unfortunately, these devices have a limited field of vision, must be attached to a firearm or bow, or are unable to provide hold over ballistic information. Thus, hunters are unable to avail themselves of the beneficial aspects of handheld rangefinders, such as increased field of vision, maneuverability, and portability, while correcting for range, slope, elevation, and rangefinder orientation utilizing hold over ballistic information.